Mic'ing 2 instruments to a single amp

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Re: Mic'ing 2 instruments to a single amp

Post by Bob Bickerton »

resistorman wrote: Thu Aug 18, 2022 3:19 am
Bob Bickerton wrote: Wed Aug 17, 2022 11:51 pm
Mike Stranks wrote: Wed Aug 17, 2022 10:11 pm As already advised, XLR Y leads are not a good idea for 2:1 microphone use...

In your situation, I'd use a mic combiner. I have the IMG Stageline version which works well. EMO do a classier - and more expensive - one, the E345.

If you're in the UK...

https://www.ebay.co.uk/itm/155111658667 ... A#shpCntId

That looks like a handy little thing - not wired to pass phantom power unless ordered from Canford.

And actually Canford have an ex-demo model available for a similar price: https://www.canford.co.uk/Products/98-1 ... ER-ex-demo

Bob

It does look good, but the original post implies that they want to switch between two instruments, this would leave both mics hot.

Quite. (I was thinking that was interesting for my own purposes)

I guess Sonics’ suggestion of a second preamp and running both at line level through a splitter like the Lehle Little would be best.

Bob
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Re: Mic'ing 2 instruments to a single amp

Post by Wonks »

What equipment are you using? What valve preamp and what amp?

'Valve preamp' could range from a £60 Behringer MIC300 to a £4k+ Avalon VT737SP. If the former, you'd probably get just as good a sound from a £100 mixer. If the latter, then it's probably wasted on live sound!

And don't forget that 'valve' does not necessarily mean 'better', especially at the budget end of the market. It's normally there to add 'character', which equated to adding some distortion to the sound. Otherwise they pretty much give the same sound as solid-state preamps do, but with a touch less fidelity. This may suit the dobro sound in some situations,in others it may not.

So knowing the equipment used would help to get a better grasp of your budget and solutions.

As MarkOne said, what may be worthwhile improvements in the signal chain at studio recording level may be completely wasted through a typical PA system.
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Re: Mic'ing 2 instruments to a single amp

Post by Hugh Robjohns »

A two in, one out balanced selector switch is easy to do for line level signals, and for dynamic (or self-powered) mic signals. Palmer and Radial both have stomp pedals that do this, and there are probably many others.

The issue is doing it with phantom powered mics when power comes from the destination preamp, because a simple switch will also switch power to the mics resulting in loud pops and bangs etc.

One way around this would be to use a dual channel phantom power supply upstream of a dynamic mic selector box, and turn off phantom from the preamp. So the two mics connect to the phantom psu, the two outputs from the pgantom psu connect to the switcher, and the switcher output feeds the preamp.

A better solution, technically, would be to use two preamps, or a dual channel mic preamp, with a line-level selector working on the outputs of the preamp.

But the cheapest solution would still be a compact mixer.

And the ideal solution would be a bespoke all-in-one system of my first suggestion. A unit which provides phantom power to two mic inputs, with electronic selection/muting of a single output. No doubt Orchid or some other custom gear designer could rustle something suitable.
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Re: Mic'ing 2 instruments to a single amp

Post by Dobrologist »

Wonks wrote: Thu Aug 18, 2022 11:17 am What equipment are you using? What valve preamp and what amp?

I don't have easy access to my equipment, so some of this info is via google search and looking through pictures.

With that in mind, my pre-amp appears to be an ART (Applied Research and Technology) .... an older version of this: https://www.americanmusical.com/art-tub ... _ZEALw_wcB
My amplifier is a Peavey Ecoustic 112 that has been modified to a single cone instead of the standard coaxial cone speaker.
I have 2 microphones. One is an Apex 165 while other is an Audio-Technica Pro 35. Both are condenser mics.

I'd like to thank everyone for their assistance so far. From what I've been able to gather, and find at all the online music stores, I'm leaning towards a powered mini mixer and hope wherever I go to purchase gives me a fair trade-in on my pre.
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Re: Mic'ing 2 instruments to a single amp

Post by Wonks »

It’s probably the most cost-effective path to take, if not quite as quick to turn one channel off and the other on as with a dedicated switch unit.

When you say ‘powered mixer’, I’m assuming you mean a mixer with phantom power rather than a mixer with a built-in power amp.

Just beware that on some small budget mixers, the phantom power provision is very limited and there isn’t enough overall current available to power more than one or two condenser mics, even if there are 4 mic inputs.

Different condenser mics take different amounts of current from the phantom circuit, so it’s hard to say whether a given mixer will support x number of phantom powered mics and it’s rate to see any mention of the maximum phantom power current available in the specs.

So I’d take all your mics along to the store when looking for a mixer, plug them all in and make sure they all work.

Was there a specific reason the co-ax speaker was changed for a single one? The HF unit was a soft-domed tweeter, not a cheaper piezo unit, so unless it was damaged, should have sounded OK. With a single 12” speaker, you’ll normally be limited to maybe 6kHz at best and will be loosing a lot of the high-end detail in the sound. The only exception I know of is the Celestion F12-X200 which does go up to 20kHz as the original Peavey unit claimed to (though even the Celestion is really a coaxial unit with a small compression driver for the high frequencies).
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Re: Mic'ing 2 instruments to a single amp

Post by Dobrologist »

Yes, the coaxial cones were damaged beyond repair. My tech guy couldn't find a coaxial speaker within budget.

And yes, I mean a mixer with phantom power.
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Re: Mic'ing 2 instruments to a single amp

Post by Bob Bickerton »

Just a wee follow up. Inspired by this thread I came across the Audio Technica AT 8681 (https://www.audio-technica.com/en-us/at8681)

Image

It’s no longer in production but I managed to find old stock in Canada and have one underway. Looks like a handy compact solution.

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Re: Mic'ing 2 instruments to a single amp

Post by Mike Stranks »

Good find Bob! As an AT fan I should have remembered that!

Available in the UK at: https://www.justmics.co.uk/audio-techni ... 2x24937344
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Re: Mic'ing 2 instruments to a single amp

Post by Bob Bickerton »

Get in fast if anyone wants one - they're rare as hen's teeth.......

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Re: Mic'ing 2 instruments to a single amp

Post by Wonks »

Though the main mic input’s phantom power circuit then has to power two mics and the mini mixer. Whilst a lot probably would, there will be some that can’t.
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Re: Mic'ing 2 instruments to a single amp

Post by Hugh Robjohns »

Quite so.

The combiner draws 2-4mA, leaving at most 3 or 4mA per connected mic. That's enough for many, but certainly not all. This combiner is designed for AT's Unipoint conference mics, and the ones I checked pull only 2mA.
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Re: Mic'ing 2 instruments to a single amp

Post by Bob Bickerton »

I'm using dynamics ;)

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